Hydrocarbon conversion process



March 9, 1965 J. A. ROBBERS HYDROCARBON CONVERSION PROCESS Filed Dec. 28, 1962 LIGHT GASOLINE HEAVY GASOLIN E LIQUID LIGHT GASOLINE HEAVY GASOLINE FEED 45 1 43 NH; I H2O INVENTOR JAMES A. ROBBERS LIQUID PRODUCT FIG.2

United rates Patent 3,172,836 HYDROCARBON CONVERSION PROCESS James A. Robbers, Lafayette, Calif., assignor to California Research Corporation, San Francisco, Calif., 21 corporation of Delaware Filed Dec. 28, 1962, Ser. No. 247,967 4 Claims. (Cl. 208-59) Introduction This invention relates to a hydrocarbon conversion process, and, more particularly, to a process for the catalytic conversion of petroleum distillates to produce high fuel value products, including gasoline.

Prior art It is well known that two-stage hydrocracking processes, i.e., processes in which contaminants are removed from a hydrocarbon feed in a first conversion zone, and the decontaminated feed is hydrocracked in a second conversion zone, are extremely versatile and valuable in modern refineries. Generally, a two-stage hydrocracking process is required because of the nature of the feed stock employed; for example, a feed with a high nitrogen content generally must be hydrofined in a first stage before being hydrocracked in a second stage of the two-stage process. Such conventional two-stage installations are practicable for large-size plants; however, with smaller hydrocracking plants, the cost of the plant, in terms of dollars per barrel of fresh feed, is quite high. Heretdfore, no reasonably practicable method of simplifying the design of such two-stage plants to render them economical for relatively small operations has been available. Heretofore, in two-stage hydrocracking plants, it has been generally necessary to use a complete system of auxiliary equipment for each of the two stages or conversion zones.

By complete system of auxiliary equipment is meant the usual equipment auxiliary to a catalytic reactor, including feed pump, heat exchange means, feed furnace, separator drum, recycle and make-up gas compressors,

etc.

With small plants, for example those having a fresh hydrocarbon feed rate of less than 5000 barrels per day, the unit cost of a reactor and each of the aforesaid items of auxiliary equipment, in terms of dollars per barrel of hydrocarbon feed, is substantially greater than the corresponding unit costs associated with larger plants.

Objects In view of the foregoing, it is an object of the present invention to provide the advantages of two-stage hydro cracking without using a complete system of auxiliary equipment for each conversion zone, so that duplication of many items of small equipment can be avoided, with a resulting substantial reduction in plant cost in terms of dollars per barrel of fresh hydrocarbon feed.

Drawings The invention will be more clearly understood, and further objects and advantages thereof, will be apparent from the following description when read in conjunction with the attached drawings, in which:

FIG. 1 is a diagrammatic illustration of an embodiment of process units and flow paths suitable for carrying out the process of the present invention, with the conversion zones being located in one reactor shell.

FIG. 2 is a diagrammatic illustration of process units and flow paths suitable for carrying out the process of the present invention with the conversion zones being located in separate reactor shells.

Statement of invention In accordance with the present invention there is provided a method of operating a hydrocarbon conversion reactor, said reactor comprising a single vertically elongated pressure shell, a first bed of catalyst located in a lower portion of said shell, said catalyst comprising a support and at least one component selected from the group consisting of Group VI metals and compounds thereof and at least one component selected from the group consisting of Group VIII metals and compounds through said first bed of catalyst, maintaining said first bed of catalyst at a temperature about from 400900 F. and at a pressure of at least 200 p.s.i.g., withdrawing from said first bed of catalyst at least one normally gaseous fraction and at least one normally liquid hydrocarbon fraction, passing at least a portion of said normally liquid hydrocarbon fraction downwardly through said second bed of catalyst together with at least 500 s.c.f. of hydrogen per barrel of liquid hydrocarbon entering said second bed of catalyst, maintaining said second bed of catalyst under hydrocracking conditions including a temperature of about from 400-900 F. and a pressure of at least 200 p.s.i.g., separating in said liquid-vapor separation zone the efiluent from said second bed of catalyst into a portion that is a liquid under the operating conditions in said second bed of catalyst and a portion that is a vapor under the operating conditions in said second bed of catalyst, recovering said liquid portion from said liquidvapor separation zone as a product, and passing said vapor portion from said liquid-vapor separation zone through said first bed of catalyst together with said hydrocarbon feed.

Feed

The feed stocks employed in the present invention preferably boil over a range of a least 50 F. within the aforesaid boiling ranges, suitable feed stocks including those heavy distillates normally defined as heavy straight run gas oils and heavy cracked cycle oils as well as conventional FCC feed and portions thereof. Cracked stocks may be obtained from thermal or catalytic cracking of various stocks including those obtained from petroleum, gilsonite, shale and coal tar. Residual feeds may boil above 500 F. and may include, for example, paraifinio residua boiling above about l050 F.

Nitrogen content of feed While the process of the invention can be practiced with utility in connection with hydrocarbon feeds to the second conversion zone which contain relatively large quantities of nitrogen, the operation becomes much more economical when the stock entering the second conversion zone from the first conversion zone contains less than 500 parts per million (p.p.m.), preferably less than ppm, and much more preferably less than 10 ppm. total nitrogen. A reduction in nitrogen content of the feed stock entering the second conversion zone permits the hydro cracking reaction in that zone to be conducted at lower temperatures than with stock containing relatively large amounts of nitrogen compounds. Accordingly, it is preferable to adjust the operating conditions in the first conversion zone to remove sufiicient nitrogen from the feed to produce a feed stock to the second conversion zone that has a sufficiently low nitrogen content, as aforesaid.

First conversion zone Denitrification of the feed to the process is accomplished in the first conversion zone by catalytic hydrogenation (hydrofining), which may be accompanied by hydrocracking. This hydrofining is accomplished by contacting the feed at temperature of from about 400 to 900 F., preferably from 500 to 800 F., pressures of at least 200 p.s.i.g., liquid hourly space velocities of from about 0.3 to 5.0 along with at least 500 act. of hydrogen per barrel of feed, with a sulfur-resistant hydrogenation catalyst. This first conversion zone hydrogenation catalyst comprises at least one Group VI metal or compound thereof and at least one Group VIII metal or compound thereof together with a suitable support. Especially preferred catalysts are nickel sulfide and molybdenum sulfide on an alumina support, and nickel sulfide and tungsten sulfide on a silica-magnesia support.

Second conversion zone In the second conversion zone the hydrocarbon feed from the first conversion zone is contacted with at least 500 s.c.f. of hydrogen per barrel at a. temperature of about from 400 to 900 F., preferably 500 to 800 F., and a pressure of at least 200 p.-s.i.g., preferably about from 800 to 3000 p.s.i.g., with a catalyst comprising one Group VIII metal or compound thereof and an active cracking support. Especially preferred catalysts are nickel sulfide on a silica-alumin support and nickeltungsten on silica-magnesia support. It is especially preferred that the latter catalyst contain fluoride. Operating temperature in the second conversion zone during the onstream period preferably is maintained at as low a value as possible consistent with maintaining adequate per-pass conversions as catalyst fouling progresses. While those skilled in the art will realize that the desired initial and terminal temperatures will be influenced by various factors including character of feed and catalyst, generally speaking, it will be desirable to operate the process with an initial on-stream temperature of about from 500 to 650 F. with a progressive increase to about 750 to 800 F., to maintain substantially constant conversion of at least 25 volume percent, preferably 35 :to 90 volume percent per pass, of the hydrocarbon feed to the second con version zone to products boiling below the initial boiling point of that feed.

Process operation Referring now to FIG.1, there shown is an exemplary overall process flow diagram suitable for carrying out the process of the present invention, with the conversion zones being located in a single reactor shell.

First conversion zone 1, which may be a bed of nickel sulfide-tungsten sulfide on silica-magnesia catalyst or a bed of nickel sulfide-molybdenum sulfide on alumina catalyst, and second conversion zone 2, which may be a bed of nickel sulfide on silica-alumina catalyst, are located within a single reactor shell 3. Second oonversion zone 2 is supported on a catalyst bed supporting grid 4, which, with separator 5, and the walls of reactor shell 3, defines a vapor-liquid separation zone 6.

The aforesaid hydrocarbon feed is passed through line and suitable distribution means 11 into first conversion zone I and is contacted there with the aforesaid first conversion zone catalyst under the aforesaid first conversion zone conditions, in the presence of hydrogen entering first conversion zone 1 through line 12, as hereinafter discussed.

From first conversion zone 1 an ammon1a-conta1nmg effluent is passed through line 13 to separation and scrub bing zone 14. In zone 14 water entering through line 15 is used to scrub ammonia from the incoming hydrocarbon stream, and the ammonia and water are withdrawn from zone 14 through line i6.

From zone 14 a hydrogen recycle stream is passed through lines 17 and 18 to second conversion zone 2. Fresh hydrogen make-up may be supplied through line 19 as required.

From zone 14 a denitrified hydrocarbon stream is passed through line 20 to separation zone 25 where it is separated into various fractions including a light gas fraction which is withdrawn through line 26, a light gasoline fraction which is withdrawn through line 27, a heavy gasoline fraction which is withdrawn through line 28, and a fraction boiling generally above the heavy gasoline range which is passed through line 13 to second conversion zone 2.

in second conversion zone 2 the denitrified feed and hydrogen entering through line 18 are contacted with the aforesaid second conversion zone catalyst under the aforesaid second conversion zone hydrocracking conditions. From second conversion zone 2 the efiluent is passed into vapor-liquid separation zone 6. Under the temperature and pressure conditions existing in zone 6, a separation of liquid and vapor will take place. The separated liquid is withdrawn through line 35 as a product or for distillation and/or further processing if desired. The separated vapor, comprising a substantial quantity of hydrogen, is passed through lines 12 and 10 into first conversion zone 1.

From the foregoing, it will be noted that conversion zones 1 and 2 do not each require a complete system of auxiliary equipment, for example a single gas circulation system serves both conversion zones. Other process ad vantages will be apparent to a man skilled in the art.

Referring now to FIG. 2, there shown is an exemplary overall process flow diagram suitable for carrying out the present invention, with first conversion zone 1 and second cgnltl ersion zone 2 each being located in a separate reactor s e The aforesaid feed is passed through line 40 into first conversion zone 1 and is contacted there with the aforesaid first conversion zone catalyst under the aforesaid first conversion zone conditions, in the presence of hydrogen entering first conversion zone 1 through lines 41 and 40, as hereinafter discussed.

From first conversion zone 1 an ammonia-containing effluent is passed through line 42 to separation and scrub- =bing zone 43. In zone 43 water entering through line 44 is used to scrub ammonia from the incoming hydrocarbon stream, and the ammonia and water are withdrawn from :zone 43 through line 45. From zone 43 a hydrogen recycle stream is passed through lines 50 and 51 to second conversion zone 2, being augmented by fresh hydrogen make-up passed through line 52 as desired.

From separation zone 43 the denitrified hydrocarbon feed is passed through line 53 to separation zone 54 where it is separated into various fractions, including a light gas fraction which is withdrawn through line 55, a light gasoline fraction which is withdrawn through line 56, a heavy gasoline fraction which is withdrawn through line 57, and a fraction boiling generally above the heavy gasoline boiling range which is passed through lines 58 and 51 to second conversion zone 2.

In second conversion zone 2 the denitrified feed and hydrogen entering through line 51 are contacted with the aforesaid second conversion zone catalyst under the aforesaid second conversion zone hydrocracking conditions. From second conversion zone 2 the effluent is passed through line 59 to vapor-liquid separator 60, where vapor and liquid are separated by vapor flashing under the conditions prevailing in zone 60.

From zone 60 the separated vapor, containing a substantial amount of hydrogen, is passed through lines 41 and 40 to first conversion zone 1. From zone 60, the separated liquid is withdrawn through line 65 as a product or for distillation and/ or further processing as desired.

As in the case of the embodiment in FIG. 1, it will be noted that conversion zones 1 and 2 do not each require a complete system of auxiliary equipment, for example a single gas circulation system sufiices for both zones. The process of the present invention permits use of a smaller bed of catalyst in the first conversion zone, and less associated heat exchange equipment, because of the removal of a large amount of liquid from the eflluent from the second conversion zone. With earlier and less active prior art catalysts than those used in the present process, this was not possible to nearly as great an extent, because smaller amounts of liquid were present. ther process advantages will be apparent to a man skilled in the art.

Although only specific embodiments of the present invention have been described, numerous variation can be made in these embodiments without departing from the spirit of the invention and all such variations that fall within the scope of the appended claims are intended to be embraced thereby.

I claim:

1. The method of operating a hydrocarbon conversion reactor, said reactor comprising a single vertically elongated pressure shell, a first bed of catalyst located in a lower portion of said shell, said catalyst comprising a support and at least one component selected from the group consisting of Group VI metals and compounds thereof and at least one component selected from the group consisting of Group VIII metals and compounds thereof, a second bed of catalyst located at an upper portion of said shell, said catalyst comprising an active cracking support and at least one component selected from the group consisting of Group VIII metals and compounds thereof, and a liquid-vapor separation zone located between said two catalyst beds, said method comprising the steps of passing a hydrocarbon feed selected from the group consisting of hydrocarbon distillates boiling above about 350 F. and hydrocarbon residua downwardly through said first bed of catalyst, maintaining said first bed of catalyst at a temperature about from 400-900 F. and at a pressure of at least 200 p.s.i.g., Withdrawing from said first bed of catalyst at least one normally gaseous fraction and at least one normally liquid hydrocarbon fraction, passing at least a portion of said normally liquid hydrocarbon fraction downwardly through said second bed of catalyst together with at least 500 s.c.f. of hydrogen per barrel of liquid hydrocarbon entering said second bed of catalyst, maintaining said second bed of catalyst under hydrocracking conditions including a temperature of about from 400900 F. and a pressure of at least 200 p.s.i.g., separating in said liquid-vapor separation zone the efiluent from said second bed of catalyst into a portion that is a liquid under the operating conditions in said second bed of catalyst and a portion that is a vapor under the operating conditions in said second bed of catalyst, recovering said liquid portion from said liquid-vapor separation zone as a product, and passing said vapor portion from said liquid-vapor separation zone through said first bed of catalyst together with said hydrocarbon feed.

2. Method as in claim 1 wherein the catalyst in said first bed of catalyst comprises nickel sulfide, molybdenum sulfide and alumina.

3. Method as in claim 1 wherein the catalyst in said first bed of catalyst comprises nickel sulfide, tungsten sulfide and silica-magnesia.

4. Method as in claim 1 wherein the catalyst in said second bed of catalyst comprises nickel sulfide and silica-alumina.

References Cited by the Examiner UNITED STATES PATENTS 2,799,626 7/57 Johnson 208- 2,885,346 5/59 Kearby et al 208--1l0 2,944,005 7/60 Scott 208---109 2,987,467 6/61 Keith et a1. 208-58 3,026,260 3/62 Watkins 20859 3,132,087 5/64 Kelley et al. 208-59 ALPHONSO D. SULLIVAN, Primary Examiner. 

1. THE METHOD OF OPERATING A HYDROCARBON CONVERSION REACTOR, SAID REACTOR COMPRISING A SINGLE VERTICALLY ELONGATED PRESSURE SHELL, A FIRST BED OF CATALYST LOCATED IN A LOWER PORTION OF SAID SHELL, SAID CATALYST COMPRISING A SUPPORT AND AT LEAST ONE COMPONENT SELECTED FROM THE GROUP CONSISTING OF GROUP VI METALS AND COMPOUNDS THEREOF AND AT LEAST ONE COMPONENT SELECTED FROM THE GROUP CONSISTING OF GROUP VIII METALS AND COMPOUNDS THEREOF, A SECOND BED OF CATALYST LOCATED AT AN UPPER PORTION OF SAID SHELL, SAID CATALYST COMPRISING AN ACTIVE CRACKING SUPPORT AND AT LEAST ONE COMPONENT SELECTED FROM THE GROUP CONSISTING OF GROUP VIII METALS AND COMPOUNDS THEREOF, AND A LIQUID-VAPOR SEPARATION ZONE LOCATED BETWEEN SAID TWO CATALYST BEDS, SAID METHOD COMPRISING THE STEPS OF PASSING A HYDROCARBON FEED SELECTED FROM THE GROUP CONSISTING OF HYDROCARBON DISTILLATES BOILING ABOVE ABOUT 350* F. AND HYDROCARBON RESIDUA DOWNWARDLY THROUGH SAID FIRST BED OF CATALYST, MAINTAINING SAID FIRST BED OF CATALYST AT A TEMPERATURE ABOUT FROM 400*-900*F. AND AT A PRESSURE OF AT LEAST 200 P.S.I.G., WITHDRAWING FROM SAID FIRST BED OF CATALYST AT LEAST ONE NORMALLY GASEOUS FRACTION AND AT LEAST ONE NORMALLY LIQUID HYDROCARBON FRACTION, PASSING AT LEAST A PORTION OF SAID NORMALLY LIQUID HYDROCARBON FRACTION DOWNWARDLY THROUGH SAID SECOND BED OF CATALYST TOGETHER WITH AT LEAST 500 S.C.F. OF HYDROGEN PER BARREL OF LIQUID HYDROCARBON ENTERING SAID SECOND BED OF CATALYST, MAINTAINING SAID SECOND BED OF CATALYST UNDER HYDROCRACKING CONDITIONS INCLUDING A TEMPERATURE OF ABOUT FROM 400*-900*F. AND A PRESSURE OF AT LEAST 200 P.S.I.G., SEPARATING IN SAID LIQUID-VAPOR SEPARATION ZONE THE EFFLUENT FROM SAID SECOND BED OF CATALYST INTO A PORTION THAT IS A LIQUID UNDER THE OPERATING CONDITIONS IN SAID SECOND BED OF CATALYST AND A PORTION THAT IS A VAPOR UNDER THE OPERATING CONDITIONS IN SAID SECOND BED OF CATALYST, RECOVERING SAID LIQUID PORTION FROM SAID LIQUID-VAPOR SEPARATION ZONE AS A PRODUCT, AND PASSING SAID VAPOR PORTION FROM SAID LIQUID-VAPOR SEPARATION ZONE THROUGH SAID FIRST BED OF CATALYST TOGETHER WITH SAID HYDROCARBON FEED. 